The DoF of Two-way Butterfly Networks

TL;DR

This paper investigates the degrees of freedom in two-way butterfly networks, revealing that bidirectional links do not enhance capacity, but caching and additional antennas can significantly improve it.

Contribution

It provides the first example where bidirectional links do not increase degrees of freedom and shows how caching or extra antennas can double the capacity.

Findings

Bidirectional links do not increase degrees of freedom.

Caching at relays can double the degrees of freedom.

Adding antennas at relays enhances network capacity.

Abstract

This paper studies the two-way butterfly network, a class of two-way four-unicast networks. We first show that bidirectional links do not increase the degrees of freedom for this network thus giving the first example for networks, to the best of our knowledge, where bidirectional links do not increase the degrees of freedom. Further, we see that sufficient caching at the relays or increasing the number of antennas in the relays can double the two-way degrees of freedom for butterfly network.